Dealers when they meet new users who have no experience with the drug, especially a powerfully addictive one .... usually give the first few doses for free.
Hopelessly addicting someone to a drug for life far outweighs the little you lose by giving them the first few doses for free.
Pharmaceuticals do the same thing by handing out free samples of new medications to doctors who give them for free to patients. This was the sales model that set off the whole opioid epidemic we're dealing with now.
That's why that Klingon is working in a crappy side street stall .... she's got a terrible sales strategy. The Klingon Empire would benefit from taking a page from Purdue Pharma.